Paleo Diet and Autism: Piecing It Together

Paleo Diet and Autism: Piecing It Together

paleo diet and autism

Autism spectrum disorders (ASD) are characterized by impairment in social interactions, communication deficits, and restricted repetitive interests and behaviors. Gluten-free, Casein-free (GFCF) diets have shown to have a remarkable effect on children with ASD, but some of what I believe to be the most important underlying factors in the etiology of the disorder is still largely unknown.

In this article, you will find other possible overlooked factors in autism, the case for the Paleo Diet and Autism, and why it may be an even more powerful therapy beyond the GFCF Diet.

Autism: The Facts

According to AutismSpeaks.Org:

•  Autism now affects 1 in 68 children and 1 in 42 boys
•  Autism prevalence figures are growing
•  Autism is the fastest-growing serious developmental disability in the U.S.
•  Autism costs a family $60,000 a year on average
•  Boys are nearly five times more likely than girls to have autism
•  There is no medical detection or cure for autism

In the 1970s and 1980s, it was estimated by the CDC that one out of every 2,000 children had autism.

The alarming increase noted by the Autism Speaks may be due to two factors: one may be due to the expansion of the definition of autism to include a larger collection of brain development disorders such as Asperger’s syndrome, or two, ASD is actually on the rise. Or… perhaps a combination of one and two are happening simultaneously.

Either way, if you are anything like me, a little red flag raises in your head anytime you hear about a ‘genetic’ disease that is increasing at a rate that is disproportionate to the population. Despite the widely accepted belief that Autism is a genetic condition, we have to ask ourselves: Is there an environmental trigger at play, as well?

Autism: The Obvious Clues


autism and gestational diabetesHyperinsulinemia is a precursor to insulin resistance, and Type II diabetes is a condition which is characterized by excess levels of insulin in the bloodstream. But it is apparent in some studies that both Type II Diabetes and autism may share a common underlying mechanism of impaired glucose and hyperinsulinemia. Rice University Biochemist Michael Stern noted that “gestational diabetes was the most important identified maternal risk factor for autism, but that no known mechanism could account for [it].”


autism and the paleo diet, autism and grainsNew research adds to the evidence of a potential link between autism and sensitivities to gluten. The researchers found that elevated antibodies to gluten were significantly more common among children with autism than in the control group. In addition, the elevated antibody levels corresponded to GI symptoms such as abdominal pain and constipation may suggest an underlying mechanism of intestinal permeability or immunological abnormalities in affected children.


dairy and autism, casein and autism In this Food Allergy and Infantile Autism study, children with ASD were found to have significantly higher levels of IgA antigen-specific antibodies for casein, lactalbumin, beta-lactoglobulin, and IgG and IgM for casein than those in the control group of 20 healthy children. This may suggest an underlying food allergy or immunological activity associated with caseinates in affected children.


Autism and GI Problems: Overlooked Clues?

paleo diet and autismIn this study, increased autism severity is associated with increased GI problems.  Parents reported significantly more GI problems in children with ASD, especially those with Full Autism, than in their unaffected children. The study also indicated that increased autism symptom severity correlated with increased severity of GI problems.

In this study which looked at differences of the gut microflora in ASD children and healthy children, it was noted that of the affected children in the study, many with ASD “had undertaken numerous courses of antibiotic treatment from an early age and suffered from common GI disorders (the most frequent complaints being [diarrhea] and/or constipation).”

clostridium and autism In this study that investigated the microflora of autistic children and control children, Finegold et al. found several differences between the two groups, including higher levels of gram-negative Firmicutes, Desulfovibrio species, and Bacteroides vulgatus in the severely autistic groups, with depressed levels of the gram-positive, regulatory, and indigenous Bifidobacterium.

In this 2005 study of the fecal flora of ASD patients by the School of Food Biosciences at the University of Reading, Whiteknights, it was discovered that ASD patients had a statistically significant higher incidence of the bacteria Clostridium histolyticum than that of healthy children.

•  C. histolyticum is a gram-negative species of bacteria that are pathogenic in humans, and has been shown to be a cause of gas gangrene (click here to see what that looks like). C. histolyticum bacteria are also known as toxin producers and contributors to gut dysfunction. This study shows that the toxigenicity of the C. histolyticum is directly related to its spore-forming abilities. The higher the spore-forming ability, the more toxigenic the strain. It is also noted in this study that toxigenic strains have a greater growth potential than nontoxigenic strains.

Clostridia groups also produce spores. Clostridia spores are impervious to most antibiotic treatments and can even withstand environmental assaults like high temperature, high UV irradiation therapies, and chemical damages.

 Clostridia groups are propionate producers. And although there have been no human studies with propionates and how that correlates to autistic symptoms, in vivo studies have indicated that injecting propionate into rats caused significant behavioral problems.

Treatment studies using the antibiotic vancomycin to treat abnormal gut flora showed significant improvements in behavior in children with Autism, but they were only temporary. As soon as they stopped the rounds of antibiotics, the benefits stopped.

Autism: Genetic Disorder, or Metabolic Disorder?

The glaring,  often under-appreciated, and direct correlation in severity of autistic symptoms with GI symptoms led the researchers who published this study in the Journal of Gastroenterology to conclude that gut dysbiosis may in fact be a causal factor in autistic symptoms— especially in light of the effectiveness of the vancomycin treatment in behavioral symptoms of ASD, and subsequent loss of benefits after treatment ended.

But what of the reported link between autism and hyperinsulinemia by Michael Stern? What could Autism possibly have in common with a disease of insulin-resistance, like Type II Diabetes?

First, in one of the aforementioned clues, we saw that there was a marked decrease in one particular type of bacteria, called Bifidobacterium. In this study, it is indicated that Bifidobacterium are regulatory bacteria, and they protect against the overgrowth of pathogenic bacteria like Clostridia groups. In fact, an increase in Bifidobacterium results in a decrease of pro-inflammatory endotoxins produced by Clostridia, like lipopolysaccharides (LPS).

Lipopolysaccharides are molecules consisting of a lipid (lipo) and complex (poly) sugar (saccharides) and are found on the outer membrane of gram-negative bacteria. Lipopolysaccharides are known as immunogenic toxins.

Studies have shown that metabolic endotoxemia from LPS can induce insulin resistance… and obesity. The other clue is how gut dysbiosis can alter the integrity of the tight junctions of the intestinal epithelium, creating the condition we call intestinal permeability.

According to this study, some Clostridia groups also produce enterotoxins that can degrade the intestinal epithelium as well.  Due to an increase in intestinal permeability, there is a subsequent increase in the passage of LPS into the systemic circulation. The result is an up-regulation in serum insulin levels.

Initially, this up-regulation of insulin sounds like bad news until you realize that it is protective because acute hyperinsulinemia actually restrains endotoxin-induced systemic inflammatory responses. Though insulin has gotten a bad rap, it turns out insulin is actually an anti-inflammatory hormone. Unfortunately, chronic insulin activity leads to insulin resistance… and the condition we know as Type II Diabetes.

This, I believe, is the underlying mechanism that Biochemist Michael Stern was missing.

Paleo Diet and Autism: Why this could work

Autism could simply be a perfect storm of environmental triggers in tandem with a genetic predisposition.  While the genetic predisposition cannot be changed, the environmental triggers may be controllable.

Many parents have seen remarkable changes in behavior by simply adhering to a gluten-free and casein-free diet, but I surmise that a Paleo Diet would work even better towards normalizing gut flora and function for children with ASD.

The Paleo Diet inherently eliminates gluten and dairy, but it also eliminates other foods that have been flying under the public consciousness radar which also elicit immunoreactivity, like corn which is the most common, non-glutenous “alternative” to wheat used in “Gluten-free” products,  millet and sorghum, and even rice.

But another key clue to why the Paleo Diet works for children with ASD is because according to this study which examines impaired carbohydrate digestion and dysbiosis, 93% of the children studied with ASD have disaccharidase and disaccharide transporter deficiencies.

Disaccharidases are enzymes that break down complex sugars (like lactose) into simple sugars (like glucose) so that the intestine can absorb the nutrients. Disaccharidase deficiency can be caused by an intestinal mucosal injury, such as autoimmune diseases, toxins, and even extended use of antibiotics. A deficiency of these enzymes in the duodenum results in a range of gastrointestinal symptoms… and gut dysbiosis.

If disaccharidases or disaccharide transporters are not present after the ingestion of complex sugars, it results in a supply of additional growth substrates for bacteria. These changes manifest in significant and specific compositional changes in the intestinal microbiota.

To put it simply, the body must break down all carbohydrates into monosaccharides before they can be absorbed. If the body cannot break down the sugars due to a deficiency in enzymes, the bacteria in your gut feeds on these sugars which leads to fermentation, which can lead to an overgrowth of potentially pathogenic bacteria like Clostridia groups, gut dysbiosis, and consequent GI distress and inflammation.

Some of the most prolific sources of complex carbohydrates (disaccharides and polysaccharides) in the Standard American Diet include Grains (and pseudo-grains), Legumes, and Dairy products, —all of which are conspicuously missing in the Paleo Diet.

This doesn’t mean the Paleo Diet is devoid of complex carbohydrate foods, but those that are sources of complex carbohydrates in the Paleo Diet, such as squash, sweet potatoes, and green leafy vegetables aren’t immunogenic.  (Please correct me if you find otherwise)

What if? Implications for Diabetics

For those suffering from gut dysbiosis and subsequent hyperinsulinemia and insulin resistance, it would make sense that a low carbohydrate diet or a Paleo Diet could have a normalizing effect on the gut flora, and weight loss would occur— at least initially.

However, if the paradigm shifts to view metabolic disorders from a macrobiotic perspective, a long-term, low carbohydrate diet may prove counter-productive if the ensuring the health and proliferation of indigenous, beneficial bacteria is not taken into account.

It is apparent that not all sugars are metabolized the same way in individuals, and some sugars may be necessary and, in fact, therapeutic. I even believe that it’s possible that a high-carbohydrate diet could resolve some issues with gut dysbiosis, and increasing specific carbohydrates and normalizing gut flora may also account for the evidence of insulin sensitization and health gains in this study.

Furthermore, it may shed some light as to why the Kitavans, who subsist on a 70% carbohydrate diet do as well as they do— which would discredit any blanket badmouthing of carbohydrates in a diet similar to looking at the robust health of the Inuit population to discredit vapid criticisms of a high protein or high-fat diet.

Specifically, some carbohydrates which have shown to increase the population of gram-positive, normalizing bacteria like Bifidobacterium are called prebiotics.

Prebiotics are a nondigestible food that nourishes the beneficial microbiota. The Bifidobacterium-promoting effect of prebiotic sugars, such as inulin (fructooligosaccharides or FOS) is well established in the medical literature. In this study, a group of volunteers increased some strains of Bifidobacterium from .89% to 3.9% of the total microbiota within the space of just a few short weeks by taking 10 grams a day of inulin.

Interestingly, increased inulin intake also improved the absorption of other vitamins and minerals in rats and human subjects, alike. Most of the inulin that is mixed with probiotics in supplements comes from chicory root, however, there are several dietary sources which are easily found; such as the Jerusalem Artichoke, Jicama, bananas, dandelion root, and plantains that are abundant in FOS.

If metabolic diseases like Autism and Diabetes Type II both show similar issues of gut dysbiosis and poor gut barrier function, perhaps they could both improve with by adhering to a Paleo Diet that focuses on minimizing complex carbohydrates from grains, legumes, and dairy— while focusing on a nutrient-dense and varied diet rich in prebiotic foods.

Is Gut Dysbiosis the Smoking Gun in ASD?

Though this area of research is still embryonic at best, I believe that in light of the information known that we may find it more valuable in terms of mitigating the adverse effects of gut dysbiosis if we collectively turn our focus away from simply cutting carbs (and demonizing carbs) and calories to focusing on normalizing gut flora. I’m not only suggesting this to a paradigm shift the individual, but also to the medical professionals and researchers as well.

I am almost certain that everyone has blamed autism on everything from genetics to pesticides, to vaccinations— all of which may have some significant portion of culpability in the Autism Spectrum Disorder, but I believe that gut dysbiosis may play a much larger role than we previously thought. Hopefully, gut dysbiosis and its role in ASD  is the next frontier in ASD research.

Or maybe not. We never know what information will come to light next, but current information does give merit to anecdotal evidence of improved cognitive function in affected children who adhered to a Paleo Diet.

And while I still cannot answer whether autism is increasing disproportionately to the population, or there are simply more neurological disorders that now fall under the new definition, I think one thing is for certain… This ain’t just a genetic disorder, folks.

Paleo Diet and Autism by Karen Pendergrass




10 Responses

  1. People have been helping their children with ASD recover with the SCD and GAPS diets (grain and specific starch-free) for decades by way of healing the gut and therefore the immune system. I’m not sure Paleo (TM) should take credit for that, though I certainly don’t disparage anyone who is trying to disseminate good info on behalf of those who wish to improve the symptoms of ASD.

    • You’re probably right, though I do take issue with a few of the acceptable foods allowed on the SCD.
      That being said, you definitely have a point.
      And the truth is, Paleo is gaining a lot of momentum, and I’d like people searching for Paleo Diet and autism to discover this particular article since there’s not a ton of stuff out there yet that addresses this. I felt there should be.

  2. I completely agree. Paleo is quickly becoming a household name, and it’s a wonderful platform from which to spread the word about dietary therapy for ASD beyond GF/CF. Likewise, I wanted to add those other diet names here in comments should they help someone on their journey. Out of curiosity, what are the foods from SCD that you disagree with?

  3. Great work, Karen. Given the impacts of saccharides, it may be even more prudent to follow a combined FODMAPS and Paleo diet. Or perhaps, fecal transplants aren’t far behind for infants and children demonstrating characteristics of autism.

    • Thanks Risa, I hope fecal transplants also get more awareness in treating metabolic disorders. It certainly helped me. Maybe that’s my next post haha

  4. Sorry, but anyone who cites Autism Speaks loses points. You’d be much better served by citing an organization that actually involves people with autism in its leadership instead of continuously disenfranchising them.

    • Wow.
      So, not that you’re discrediting the work, the studies, the reason for writing this article, or the conclusions… You’re taking issue with the group I used to state facts about the prevalence and growing trend of the condition in the first paragraph.

      If you are interested in telling me what you have against Autism Speaks, fine. But don’t come telling me I lose “points” for citing them for basic factoids. That’s just stupid.

  5. Great post Karen! I am a DPT student in Australia and am currently learning about the role of a physiotherapist in ASD.

    I am a paleo advocate and have always believed in Hippocrates quote: “Let food be thy medicine and medicine be thy food”.

    It was also nice to see a heap of links to peer-reviewed journal articles to back up the statements!

    I reblogged this page on my blog: Keep up the great work! 🙂

  6. Im lost if you could explain in simpler speak what to feed a child with autism I would be grateful .
    The boy is nine years old.
    Regards Harry Hunter.

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